[sufue]

Sharpe's Siege is the 18th or 19th (depending on whether you count a couple of novellas) in Bernard Cornwell's Sharpe series. My son, who is really into military history (and fiction), loved this series. Siege has dropped to $1.99 at Kindle and Kobo US.

Kindle US: https://www.amazon.com/dp/B002UZDTGA
Kobo US: https://www.kobo.com/us/en/ebook/sharpe-s-siege-9

Spoiler:

Sharpe's mission has seemed simple: capture a small unguarded French coastal fort, cripple Napoleon's supply lines, and retreat across the sea. But behind the lines, Sharpe's old enemy, Pierre Ducos, awaits Sharpe's arrival with a battalion of French soldiers and a vicious commanding general who keeps the scalps of his dead enemies as trophies.

Outmaneuvered by Ducos's treachery and abandoned by his own navy, Sharpe has only two choices: to escape with the aid of the charming, unscrupulous American mercenary, Cornelius Killick, or die.